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Total Human Eye Allotransplantation (THEA): Developing surgical protocols for donor and recipient procedures
Edward H. Davidson, MA (Cantab.) MBBS, Eric W. Wang, MD, Jenny Y. Yu, MD, Juan C. Fernandez-Miranda, MD, Dawn J. Wang, MD, Maxine R. Miller, MD, Joel S. Schuman, MD, Kia M. Washington, MD.
University of Pittsburgh, Pittsburgh, PA, USA.
BACKGROUND:
Vascularized composite allotransplantation of the eye is an appealing novel method for restoration, replacement and reconstruction of the non-functioning eye. Our group has established the first orthotopic model for eye transplantation in the rat. Now with advancements in immunomodulation strategies together with new therapies in neuroregeneration, parallel development of human surgical protocols is vital in ensuring momentum towards eye transplantation in actual patients.
METHODS:
Cadaveric donor tissue harvest (n=8) was performed with orbital exenteration, combined open craniotomy and endonasal approach to ligate the ophthalmic artery at the suprasellar cistern, for transection of the optic nerve at the optic chiasm and for transection of occulomotor, trochlear and abducens nerves at the cavernous sinus. Superior ophthalmic and inferior ophthalmic veins were harvested at the cavernous sinus. For cadaveric recipient procedures, superficial temporal/internal maxillary artery and superficial temporal/ facial vein were exposed. Donor tissue was secured in recipient orbits followed by sequential venous and arterial anastomosis and nerve coaptation. All measurements of pedicle lengths and caliber were measured. All steps were timed, photographed, video recorded and critically analyzed after each operative session.
RESULTS:
Technical feasibility of cadaveric donor procurement and transplantation to cadaveric recipient was established. Measurements included: optic nerve pedicle length 39mm, ophthalmic artery length 13.5mm, ophthalmic artery caliber 1mm, superior ophthalmic vein length 15mm, superior ophthalmic vein caliber 0.5mm. Recipient anastomoses to superfical temporal/ internal maxillary artery (1mm/2mm caliber) and superior temporal/facial vein (1.5mm/2.5mm caliber) were achieved with standard microsurgical techniques and required vein grafting. A stem of internal carotid artery was used when arterial anastomosis was to the internal maxillary artery. Nerve coaptation was achieved with fibrin adhesive and nerve wraps.
CONCLUSIONS:
This surgical protocol serves as a benchmark for optimization of technique, potentiating the scope of face transplants to include eye tissue as well as revolutionizing the clinical management of visual impairment and blindness by introducing the possibility of vision restoration transplantation surgery.
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